Biologically Inspired and Magnetically Recoverable Copper Porphyrinic Catalysts: A Greener Approach for Oxidation of Hydrocarbons with Molecular Oxygen

An efficient synthetic method for magnetically recoverable hybrid copper porphyrinic nanomaterials is reported. These functionalized magnetic materials prove to be efficient bioinspired oxidation catalysts of olefins and thiols, using molecular oxygen as oxidant, in total absence of reductants and solvents, with the highest TON (turnover number) yet achieved for this reaction (≈200 000). A comparative study between homogeneous and heterogeneous oxidation of cyclohexene is discussed, revealing the heterogeneous system to be the most promising concerning stability and reusability of the catalysts. The full characterization of the magnetic hybrid porphyrinic nanomaterials, by transmission electron microscopy, flame atomic absorption spectrometry, thermogravimetry, N₂ sorption, and infrared spectroscopy, is also described.     

Effect of metal loading on catalytic activity and selectivity of ZSM-5 zeolite catalyst in conversion of methanol to olefins and aromatics

Effect of ZSM-5 zeolite promotion using potassium, strontium, and cerium metals on conversion of methanol to light olefins and aromatics was investigated. ZSM-5 catalyst was promoted using wet impregnation of metal salts and its activity was tested in methanol to hydrocarbons process under optimum operational condition obtained in our group previously. Zeolite samples were characterized by X-ray powder diffraction, scanning electron microscopy, N₂ adsorption-desorption, acid sites distribution, and strength using temperature programmed desorption of NH₃. Results showed that presence of these metals could significantly affect acid site distribution and therefore influence the catalyst activity and selectivity to olefins and aromatics.     

Modeling the intact form of the {alpha}1-proteinase inhibitor

The structure of the intact form of the serpin ₁-proteinaseinhibitor has been modeled based on the assumption that thecentral strand s4A of the six-stranded ß-sheet A ofthe cleaved inhibitor is not incorporated into the sheet ofintact ₁-proteinase inhibitor. This strand was removed fromits position in the center of the sheet by suitable rotationsabout the backbone dihedrals of Lys343 using molecular graphics.The resulting structure was then annealed using molecular dynamics(MD) while applying progressive distance restraints to the reactivepeptide bond (Met358-Ser359) for 50 ps. During this time, thedisrupted ß-sheet reformed to create a five-strandedß-sheet with strands 3 and 5 in a parallel arrangement.This change and accompanying structural rearrangements are largelyconfirmed by the X-ray structure of plakalbumin, whose structurereflects the overall structure of intact serpins. The successfulmodeling experiment demonstrates the utility of MD for makinggross structural predictions based on related structures. Thebinding loop of the intact form is modeled to allow dockingwith serine proteinases, in particular thrombin, which mosthighly constrains the possible conformations of the bindingloop.     

HOP INDUSTRY COMMITTEE: ANALYSIS OF HOPS OF THE 1980 CROP

Analytical values for α-acid content of thirteen varieties of hops from the 1980 crop are presented in relation to the district of production. For all varieties the tolerance aim of ±0·5% was achieved this year and variability of the crop was generally the same as the average for the last five years. As before, the results are acceptable for commercial purposes. The sampling rates have been considered and a minor reduction in the rate for Wye Target is justified.     

双酶法水解米糠淀粉的工艺研究

为了提取米糠淀粉获得葡萄糖作为纳豆芽孢杆菌液态发酵的碳源,采用α-淀粉酶和糖化酶联合水解米糠中的淀粉,在单因素试验的基础上,运用正交试验设计方法对米糠中的淀粉水解工艺进行了研究和优化.结果表明,米糠中淀粉的最佳液化工艺条件为α-淀粉酶添加量16 u/g,温度60℃,CaCl2添加量0.2％,DE值为24.31％;最佳糖化工艺条件为糖化酶添加量200 u/g,温度60℃,pH 4.0,糖化时间6h,最大DE值为98.96％.该工艺使米糠中淀粉的提取率达到了89％,并基本都水解为了还原糖,可作为纳豆芽孢杆菌液态发酵的优质碳源.     

牡蛎蛋白酶解多肽降糖及抗氧化活性评价

目的:利用化学方法评价9种酶对牡蛎蛋白酶解所得多肽降血糖和抗氧化活性的影响,筛选最佳酶的种类。方法:以牡蛎蛋白酶解多肽对α-淀粉酶抑制率为指标评价其体外辅助降血糖活性,以DPPH·清除率、超氧阴离子抑制率为指标评价牡蛎蛋白酶解多肽的体外抗氧化活性,筛选出最佳用酶。结果:风味蛋白酶得到的多肽对α-淀粉酶的抑制效果最好,5 mg/mL时抑制率达到67.13%,IC₅₀值为3.806 mg/mL;糜蛋白酶酶解得到的多肽对DPPH·的清除率最高,2 mg/mL时清除率为58.09%,IC₅₀值为1.16 mg/mL;同时,糜蛋白酶酶解得到的多肽对超氧阴离子的抑制率也最高,2 mg/mL时抑制率为53.64%,IC₅₀值为1.75 mg/mL。结论:风味蛋白酶和糜蛋白酶酶解所得牡蛎多肽在降糖和抗氧化方面具有较大的潜力,为进一步开展牡蛎蛋白酶解多肽的研究提供参考。     

苦荞黄酮对α-淀粉酶的抑制作用研究

为了比较研究各种不同提取方法下的苦荞黄酮对α-淀粉酶的抑制作用,分别对苦荞总黄酮溶液、苦荞水溶性黄酮溶液、苦荞醇溶性黄酮溶液用α-淀粉酶进行体外活性抑制作用试验,并绘制抑制曲线,所得的结果与阿卡波糖进行比较。结果表明:阿卡波糖、苦荞总黄酮、苦荞水溶性黄酮、苦荞醇溶性黄酮对α-淀粉酶均有抑制作用,其半抑制浓度(IC50)值分别为0.095、0.086、0.10、0.202 mg/mL。本研究为三种提取产物在防治糖尿病及其并发症等方面的应用提供参考,具有较大的理论意义和应用价值。     

破壁方式对蜂花粉抑制α-葡萄糖苷酶活性的影响

以不同破壁方式处理过的油菜蜂花粉为研究对象,提取水溶活性成分,以4-硝基苯-α-D-吡喃葡萄糖苷(PNPG)作为底物,对蜂花粉作为天然α-葡萄糖苷酶活性抑制剂的功效进行了评价。结果表明:破壁方式对蜂花粉功能活性成分以及功效评价结果影响显著,温差破壁、超临界二氧化碳破壁、超声辅助酶解破壁及对照组对α-葡萄糖苷酶的抑制率分别为(13.73±1.15)%,(-8.07±0.93)%,(16.70±0.87)%,(9.68±0.89)%;油菜蜂花粉多糖对α-葡萄糖苷酶的抑制率在(3.46±0.31)%~(-0.78±0.03)%,无明显线性关系;破壁后的样品多糖含量显著增加,但油菜蜂花粉多糖对α-葡萄糖苷酶活性无作用,可能与黄酮等其它成分相关。